Issue 8, 2018, Issue in Progress

Understanding viscosity reduction of a long-tail sulfobetaine viscoelastic surfactant by organic compounds

Abstract

Though the transition from cylindrical micelles to spherical micelles of the anionic surfactant potassium oleate in the presence of oils has been studied, these changes have not been studied for long-tail zwitterionic surfactants. The effects of n-decane, crude oil (CO), extra virgin olive oil (EVOO) and polyglycolic acid (PGA) on the zero-shear viscosity of an aqueous solution of a sulfobetaine surfactant system were investigated at 30 °C and 60 °C. The main surfactant in the system was erucamidopropyl hydroxypropyl sulfobetaine. The methods employed were rheology and cryo-TEM. The solution with 3.96 wt% surfactant system and 6.2 wt% CaCl2 was viscoelastic at both test temperatures due to the formation of entangled cylindrical micelle networks. n-Decane induced the following regimes of zero-shear viscosity change at both temperatures: (i) the high viscosity regime (HVR), (ii) the transition regime (TR), and (iii) the low viscosity regime (LVR). The HVR was characterized by high zero-shear viscosities. The TR was characterized by a sharp drop in zero-shear viscosity due to the formation of untangled micelles. The LVR was due to the formation of microemulsions. The formation of these regimes depended on the balance between micellization and oil solubilization. We reveal for the first time that the number of regimes depends on the type of oil: both CO and EVOO induced only one and two regimes at 30 °C and 60 °C, respectively. PGA did not significantly affect the solution at either temperature with increasing concentration, meaning the solution was resistant to decreasing pH even at higher temperatures.

Graphical abstract: Understanding viscosity reduction of a long-tail sulfobetaine viscoelastic surfactant by organic compounds

Supplementary files

Article information

Article type
Paper
Submitted
17 Nov 2017
Accepted
11 Jan 2018
First published
24 Jan 2018
This article is Open Access
Creative Commons BY license

RSC Adv., 2018,8, 4455-4463

Understanding viscosity reduction of a long-tail sulfobetaine viscoelastic surfactant by organic compounds

L. T. Fogang, A. S. Sultan and M. S. Kamal, RSC Adv., 2018, 8, 4455 DOI: 10.1039/C7RA12538K

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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